Manufacture of coal-tar composition and pitches.



UNITED STATES-J- iatented September 15, 1903 PATENT OFFICE. I

FREDERICK JOHN WARREN, OF NEWTON, MASSACHUSETTS.

MANUFACTURE OF COAL-TAR COMPOSITION AND PITCHES.

S 1 ECIFIOATION forming part of Letters Patent No. 738,966, dated September 15, 1903. Applioationfiled May 16, 1901. Serial No. 60,448. (No specimens.)

To all whom it may concern:

Be it known that I, FREDERICK JOHN WAR-.

BEN, a citizen of theUnited States, residing at Newton, in the county of Middlesex and Commonwealth of Massachusetts, have invented a new and useful Improvement in the Manufacture of Coal-Tar Composition and Pitches, of which the following is a full, clear, and exact description.

The invention relates to an improvement in coal-tar and its products-such as paving composition, pitches, &c. for use in roofing, paving; waterproofing, insulating, or for any other purpose for which coal-tar or its products may be used.

The invention is based on the discovery that a tar or-pitch that consists of nearly pure bitumen is more subject to changes of temperature than one which is relatively an impure bitumen-that is, it will flow easier when warm and will become more brittle when cold than a tar or pitch which is not so pure. This property of not being easily afiected by. extremes of temperature is especially desirable for use for roofing purposes and for similar purposes when the tar composition is subjected to the action of the elements.

The impurities ordinarily existing in the class of bitumens consists of very finely-divided amorphous carbon, similar to the lamp- 4 black of commerce; but the percentage of lampblack'existin g in the different crude tars is an exceedingly-variable quantity, varying from seven per cent. in the purest tars to as high as thirty-five per cent. in other tars, and when these tars are made into a roofing-pitch the pitch resulting therefrom will contain from eight percent. to forty-eight per cent. of lampblack. I have discovered that the presence of this impurity in tars and pitchesinstead of being a detriment, as it has generally been considered, is actually necessary to give the pitch, tar, or composition some of those qualities which are invaluable, and a proper proportion of it increases their usefulness to such an extent as to make them available for uses for which they would otherwise be unfit. Some tars might perchance contain the proper amount of lampblack to suit them for a certain use; but as the presence of this impurity in the tar is an accidental occurrence the tar from any one works will vary considerably, so that it becomes necessary in practice to make up this deficiency by additional lampblack, or if the tar in its original state should contain more lampblack than is necessary to produce the results required a tar richer in bitumen may be added to it to bring the percentage of impurities down to the required amount.

I have discovered that a tar which contains more than twenty per cent. to twenty-five per cent. of lampblack when used for making roofing-felt will not saturate the dry felt well and will leave a sticky surface, which causes wastage of the manufactured product owing to the different layers of felt in the rolls adhering to each other and on account of not saturating the felt thoroughly makes an inferior roofing-paper and one which is expensive to make. By mixing with this tar one which will reduce the impurities below the limit given the tar will saturate the paper thoroughly, leaving a comparatively non adhesive surface, and make the felt weigh more than if the saturation was not thorough. I also find that if roofing-pitch be made containing from thirtyfive per cent. to forty per cent. of lampblack its adaptability and life are greatly increased.

Paving composition may contain as high as fifty per cent. of lampblack and greatly increase the value of the composition from which it was made. My invention contemplates the addition of this lampblack to tars or compositions either during the manufacture of the crude tar, to the crude tar itself, or to the products of the tar during or after their manufacture. This may be accomplished in several ways. The amount of lampblack which may form during production of the tar may be regulated by varying the shape'of the retort or by varying the methods of making the gas or the heat at which the retorts are held during its manufacture without materially affecting the other products of distillation. It may be introduced into the crude tar in bulk and effect a mixture by means of agitation, or it may be introduced by carbonizing oil and forcing the lampblack-laden. air resulting therefrom into a mass of tar or composition, the lampblack mixing with the tar during its passage through it. I have also discovered that other impalpable carbon has the same beneficial efiect on tars or their products as lamp- 1. A method for decreasing the variation in viscosity of coal-tar cements and pitches consisting in treating the coal-tars With impa1-.

pable carbon in predetermined quantity.

2. A method for decreasing the variation in viscosity of coal-tar cements and pitches consistin g in regulating the supply of lampblack in the same to within predetermined limits.

FREDERICK JOHN WARREN. Witnesses:

F. F. RAYMOND, 2d, J. M. DOLAN. 

